Screw-wrench



C. F. MUELLER.-

SCREW WRENCH.

APPIIcATIoN FILI-:n APR. Is. 1919.

Patented May'3, 1921.

2 SHEETS-SHEET 2.

UNITED STATES CHARLES F. MUELLER, 0F ELIZABETH, NEN JERSEY.

SCREW' -W' BENCH.

Application filed April 1S, 1919.

To all whom t may concern:

Be it known that I, CHARLns F. MUnLLn a citizen of the United States, residing in Elizabeth, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Screw- Wrenches, of which the following is a specification.

This invention relates to screw-wrenches, and its object is to produce a compact, reliable, closely adjust-able, powerful device whose parts may be inexpensively made and easily fitted together or assembled.

In a well-known type of screw-wrench used by machinists, one jaw is moved by turning a nut which engages rack connected with the movable jaw. In using such wrenches, a substantial portion or nearly all of the thrust or stress is borne by this awadjusting nut, and hence it is the practice to make the same with coarse threads, for strength. Tt is also found necessary in practice for such a nut to fit loosely. Consequently, after the wrench is fitted upon a bolt-head or nut, to turn the same, there occurs a yielding of the movable jaw when the attempt is made to turn the bolt. @wing to this yielding of the movable jaw.r the wrench no longer tits closely upon the bolthead or nut, but grinds and strips the corners therefrom, this injury being more serious as the wrench is used upon smaller bolts and nuts. The expense of milling the rack in the shank of the jaw, for engagement by the jaw-adjusting nut, is also heavy.

Moreover, in using the wrench, if its nut be accidentally struck against some part of the machinery, the nut is turned, and thereby the adjustment of the jai is lost, since even a little turning of the nut effects considerable jaw movement, owing to the necessarily coarse pitch of the threads of the nut.

Another fault in common wrenches is their comparative weakness. This is noticeable in the case of large wrenches used upon large nuts, which are sometimes difficult to dislodge. In such cases. it is the practice to slip a length of pipe over the handle of the wrench` so as to lengthen said handle and give more purchase: with the result that the head of the wrench is apt to be broken.

Again, owing to the fact that the adiusting nut of the wrench has to bear a large portion of the thrust or stressy it often happens that said nut is injur-ed making it ditliV cult. to operate it, and the injury is apt to Specification of Letters Yatent.

Patented May 3, 1921.

Serial No. 290,916.

be enough to destroy the efliciency of the wrench. This is a prolific source of complaint` and loss.

Some of the main objects of the present invention, therefore, are to overcome the foregoing objections; to make it practicable tol set the movable jaw accurately; to prevent appreciable yielding of said movable jaw when subjected to the stress of turning a bolt or nut, thereby avoiding liability of stripping the corners from the bolt; to increase the strength and enlarge the capacity of the wrench as compared with previous wrenches of similar sizes; to avoid injury to the revoluble threaded member which adjusts the movable jaw, and to make it practicable to use comparatively linethreads upon said revolnble member; to reduce the cost of manufacture; to reduce or avoid the liability of throwing the wrench out of adjust-ment by accidentally striking the nut or adjuster against any object; and to increase the power of the wrench and safeguard it against injury when subjected to the severest. tests.

ln order to overcome said objections and gain said advantages, l form the movable jaw of the wrench with'a guide-shank eX- tending preferably at a right angle thereto, and forming with the movable aw an L-shaped device. This guide-shank lits in a ,Cuideway formed in the head of the wrench. This shank may not only guide the movable jaw accurately, so that it can be adjusted finely, but may also have the tendency or eiiect of making the movable aw self-binding, thereby relieving the adjusting nut (or screw) of a lai ge part of the great stress to which it has been subjected in previous wrenches. Anything which tends to separate the jaws, tends to turn the movable jaw, thus thrusting the lower end of its shank against one end of the guideway, while the upper end of the shank presses against the other end thereof; and any increase in pressure upon the jaw tends to increase the pressure of the shank at these points upon the guideway, and thereby augment the frictional opposition of the shank or jaw to being moved along the guideway. This frictional resistance or clutching action may be enough to counteract almost entirely the force which is tendingl to open thejaws, so thatundue stress may not come upon the jaw-adjusting screw or nut. 1

The adjustment of the movable jaw is effected by a screw threaded through the jaw and having at its upper end a knurled thumb-wheel turning in a recess in the head of the wrench. Said screw may extend down by the side ot the cheek of the wrench, where it is protected from injury. The screw is arranged between the movable jaw and its guide-shank, and may be closely fitted. It may have a thread ot iine pitch, so that the movable jaw may be accurately adjusted thereby; while the supporting and selt';binding action, already described, gives such a grip ot' the movable jaw upon the head of the wrench that the movable jaw does not yield appreciably when subjected to the stress of turning a bolt or nut. 1t the thumb-wheel should happen to be knocked against any part accidentally and turned thereby, the adjustment of the wrenchv would not be appreciably disturbed, because of the ineness ot the thread which it becomes practicable to provide upon the screw.

Moreover, since the strength ot the wrench depends mainly upon the strength ot' the jaw, and of the guide-shank thereon, and orn the guideway therefor, and but little upon the screw, it follows that the power of the wrench may be about doubled as compared with previous wrenches of similar size, and so that the wrench will pass successfully and without injury a test consisting in gripping and breakino' nut of nearly the full capacity ot the wrench.

1n the preferred form of the invention, a dovetail relation is provided between the movable jaw and the cheek oi' the wrench, so that they cannot be separated except by sliding the iawV out of the dovetail guide. Hence the adjusting screw also retains the jaw upon the wrench, thus conducing to simplicity and reducing cost.

Other 'features and advantages will hereinafter appear.

In the accompanying drawings,

Figure l is a view oi my improved wrench.

Fig. 2 is a view oit the head otthe wrench, showing the opposite side from Fig. 1.

Fig. 3 is a view similar to Fig. 2, but showing the jaws as nearly closed.k

Fig. l is a perspective view ot a single. forging comprising the handle, cheek and fixed jaw ot the wrench.

Fig. 5 is a perspective view of the movable aw.

Fig. 6 is sectional view, taken on the line 6-6 of Fig. 3.

7 is a side elevation; and Fig. 8 an edge view of the preferred form of wrench.

Fig. 9 is a perspective of the head of the wrench seen at Figs. 7, 8.

Fig. 10 is a perspective of the movable jaw seen at Figs. 7, 8.

Fig. 11 shows another form of retaining Fig. 14 shows another form of adjusting screw.

Fig. 15 shows another method ot retaining the adjusting screw.

rEhe wrench comprises any suitable handle 10, having a head carrying jaws 11, 12, the handle preferably extending at an angle to the direction of travel of the movable jaw, as is desirable for the use of machinists. In the form of the invention illustrated in the drawings, the top jaw 11 is fixed and the bottom jaw 12 is movable, although the invention is not limited to this relative arrangement.

The movable jaw 12 has at its inner end a right-angle shank 13, which slides up and down in a guideway 14 formed in the head o1 the wrench, said shank and guideway being placed back of the fixed jaw 11, and the guideway being in the form of a straight recess formed in theA head. The movable jaw has a plate portion or neck 15 lying against the cheek 18 and connecting the jaw properwith the shank 13; and this plate portion is bored vertically at 16 and threaded to receive a jaw-adjusting screw 17, which extends up alongside the cheek portion 18 of the head and into the base portion of the upper `iaw, the latter being recessed at 19 to receive a knurled thumb-wheel 20 rigid with the screw, for rotating the same. Preferably the screw 17 extends up through the wheel, and terminates in a short smooth shank 21, which rotates in a hole or bearing 22 formed in the head of the wrench and provided with a screw-driver nick 23, whereby the screw may be turned into the wheel, the perforation in the latter being threaded, and the screw and the wheel being rigidly joined by turning the screw with a screwdriver as tar as it will go, while holding the wheel stationary. rI'Che head may be cut away on one side at 23l around said recess, to afford access to the thumb-wheel. rlf'he plate 15 may have the same thickness as the shank 13, and the licor of the guideway 111 may be iiush with the cheek 18.

The movable jaw is held iacewise to the wrench-head by L eans of a headed pin 24, which is driven into the movable jaw near the junction of shank13 with plate 15,.said pin working` in a slot 525 formed in the cheek 18, and said slot being of a length to permit the wrench to open as tar as desired. The slot is preferably countersunk or grooved at 25a to receive the head 26 of pin 24.

The base portion of the upper jaw may be deepened at 27 to give this part of the guideway 14 suliicient length, so that the top of the shank may not escape therefrom even when the jaws are fully separated. rillhe plate portion of the lower jaw may be cut away or notched at 2S to give clearance for sait deepened portion 2T, to permit the jaws to come together.

rThe screw is held against endwise displacement by reason of its attachment to the thumb-wheel, which fits in the perforation 19 in the head; and both the screw and the threaded hole in the movable jaw may be accurately made by inexpensive methods, practically eliminating lost-motion or shake of the movable j aw, so that when it is once set to the desired point it will remain there.

if-"rs will be seen at Fig 3, the screw 17 is so located that it does not prevent the substantial closing of one jaw against the other. For this reason the screw is connected to such a portion of the movable jaw (preferably the plate or neck 15) that the screw stands alongside of the shank, to be out of the path of movement thereof, wherefore the shank can pass by the screw, as well as the wheel 2J thereonA Hence the tip of the shank 13 can project from the wrench past the fixed jaw 11` at said Fig. 3, to permit the closing of the wrench. rlhe guiding groove 14 for the shank 13 is open at the end adjacent to the fixed jaw 11, for this purpose. T he shank can move into and out of the guide at each end of the latter. Hence the wrench is eiiicicnt for all sizes of work within its widest capacity; and the line/ness of the pitch of the screw makes it particularly cesirable for use upon relatively small nuts and bolts, etc., iile, owing to the cooperation of the shank with its guides, the iineness of the pitch is not an objection to the use of the wrench upon large bolts and nuts, since the stress is taken mainly by the shank and guides, and not so much by the forew. so that threads of ne pitch are capable of performing the task. Since the groove 1f: is open at both ends, it is 'also simple to machine the guiding surfaces thereof.

When the wrench is placed in position to operate a nut or bolt, the operation tends to separate the jaws, or in oth 7 words to push the movable 12 away from the lif jaw. This tendency7 to displace the movai jaw is opposed partly by the screw 17, but mainly by the shank 13 on the movable jaw, which preferably extends up toward or to the fixed aw, and which tends to move inwardly at its lower end at point 30, and outwardly at its upper end at point 31, since the jaw tends to swing about a point in the vicinity of the lower end of the shank. rllhus it will be seen that the tendency separate the jaws produces a tendency of the shank at its lower end to bear in one direction against one side of the wall of the guidelll, and at its upper end in the opposite direction against the upper side wall of the guide, thus setting up afriction or clutching which opposes movement of the vjaw along the guide. In other words, the shank may cooperate with its guideway to set up a friction, thereby to cooperate with the screw in opposing displacement of the jaw when turning` a nut or bolt. Thus the movable jaw becomes self-binding, or in other words the shank and guideway form a clutch, whose eliiciency to oppose separation of the jaws, or to take the stress applied to the movable jaw, may be in proportion to its length as compared with the length of the shank. The proportions shown in the drawings are found suitable in practice, the length of the shank from top to bottom being substantially less than the distance from the tip of the movable jaw to the outer guide wall or point 30. The shank forms a short arm and the jaw a long arm of a bell-crank. With this self-binding or clutching action, which may be augmented, if desired, by shortening the shank or lengthening the jaws, or both, the stress arising from the operation of the wrench may be largely taken up, so that the jaw-adjusting screw may perform a minor part in withstanding the tendency of the jaws to separate, as compared with screws or nuts of previous wrenches, especially wrenches of the machinists type herein shown, in which the handle extends from the head at an angle to the direction of travel of the movable jaw.

Since the withstanding of the stress is mainly taken off from the screw and placed upon the jaw and its shank, it becomes feasible to provide a screw with finer threads than have heretofore been usual, so that accurate adjustment of the movable jaw can be readily secured; while the threads may be accurately made, and the screw readily held against endwise shake, so that there will be practically no shake of the movable jaw; while the self-binding effect, taken with the holding power of the screw, keeps the jaw from yielding appreciably, thereby overcoming objections hereinabove set forth.

rThe handle 10, the cheek 18, and the fixed jaw 11 may be formed of one forging, the lcheek being about half the thickness of the fixed jaw. By a single milling cut, the guidcway lll for the shank of the movable jaw may be finished. The slot 25 for the connecting pin and the groove 25a for the head of the pin may be inexpensively cut; and, if desired, thc hollow or depression 32 on the inner side of the cheek may be milled out or finished to make a close fit for thel boss 33 on the inside of the plate 15, where the screw is threaded through the latter. It will be seen that all parts may be accurately formed in quantities, and that they may be assembled without fitting, thus eliminating a large element of cost in manufacture.

If desired, the edge 34 of the cheek may be finished, and the overhanging side 34a of the jaw 12 may be fitted to slide thereon. However, a clearance may be left between the said edge and the jaw, if it is desired to accentuate the self-binding function of the jaw shank 13.

In the preferred form of movable jaw shown in Figs. 7 to 10, the shank 13 is provided with a guide-rib 35, which extends the length of the shank and fits in a groove or depression 36 made in the main guideway 14, thus giving additional bearing surface and therefore increasin the strength or power of the wrench. his groove 36 extends the entire length of the head, and the shank is supported thereby, as well as by the main guide 14. After the shank is adjusted down so far as to clear that side of the guide 14, which is formed at the base of the fixed jaw 11, the shank is still supported by the groove 36, thus increasing the capacity and usefulness of the wrench. Moreover, the provision of the rib and the groove tends to make the traveling jaw more rigid, so that the jaws are not apt to spread and slip around the nut, even when subjected to severe stress.

This effect is augmented by fitting the overhanging portion 37 of the movable jaw 12 to the edge 34 of the cheek, Fig. 7, whereby additional bearing surface is secured. Moreover, this overhanging portion may be undercut at 38, and the edge of the cheek may be beveled at 34b to correspond, thus cooperating with` the rib 35 and the groove 36 to make a dovetail joint between the movable jaw 12 and the cheek 18, so that the movable jaw is self-retaining upon the head, so long as the screw 17 catches any of the threads in the movable jaw. The cheek 18 occupies a position between the-rib 35 and the overhanging portion 37.

The wrench therefore is much simplified in construction, comprising one piece for the cheek, fixed head and shank, another piece for the movable jaw, and a third part consisting of the adjusting screw. Thus there `is inexpensively made a simple wrench of large capacity for its size, as well as greatly increased power, eliminating liability of injury to the screw by severe stresses.

At Figs. 11-13 is shown a wrench similar to that at Fig. 7, but the dovetail construction is not used; the movable jaw being kept in position by means of a cap plate 40, which is fitted upon said jaw and secured thereto by a screw 41, and slides in a depression 42 formed along the edge of the cheek. Y

At Figs. 8 to 12 the surface 43 of the cheek is illustrated as concave, as this form may be readily milled out, the milling cutter escaping the far edge of the guideway 14. This permits the movable jaw to be fitted closely against the cheek. The general direction of this surface 43 is diagonal at Fig. 8, thus giving a dovetail effect at both edges, since the edges are undercut at both 34b and 35El with reference to this cheek surface 43. Moreover, the inner wall of the hearing groove 36 is deeper than would be the case if the cheek 43 were a flat surface parallel with its outside face. It will be seen that the outer side wall 36a of the groove is deeper at Fig. 9 than at Fig. 4, owing to the increased depth cut therein for the rib 35; and that the opposite wall is double, giving a step-like form to the groove, increasing the bearing surface for the movable jaw, and having the other advantages already explained.

At Fig. 14 the thumb-wheel 44 forms the head of the screw, which has a shank 45 to turn in the hole 22 in the fixed aw or head The hole is counterbored at 46 to receive the thumb-wheel or screw head. By using a nut 47, the endwise play of the screw may be taken up, and such adjustment may be se- Cured by a lock-nut 48. These nuts cooperate with the screw head to retain the screw in the wrench.

At Fig. 15 the nuts 47 and 48 are omitted. The shank or bearing part of the screw has a peripheral groove 49, in which fits the point of the headed screw 50, which is threaded into the head of the wrench.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim: v

1. A wrench having a fixed jaw, a movable jaw, a single guiding connection between said jaws, comprising a shank extending transversely from the base of one of said jaws and a transverse guideway at the base of the other, and-means located between the A working portions of said jaws and said guiding connection for adjusting the movable jaw relatively to the fixed jaw.

2. A wrench having a fixed jaw, a movable jaw, a single guiding connection between said jaws, comprising a shank extending transversely from the base of one of said jaws and a transverse guideway at the base of the other, and a jaw-adjusting screw located between the working portions of said jaws and said guiding connection for adjusting the movable jaw relativelyto the fixed jaw.

3. A wrench having a fixed jaw, a movable jaw, a single guiding connection between said jaws, comprising a shank extending transversely from the base of one of 'said jaws and a transverse guideway at the base of the other, and a j aw-adjusting screw located between the Vworking portions of said jaws and said guiding connection for adjusting the movable jaw relatively to the fixed jaw, said screw having a head portion journaled in the base of'one of said jaws, and a body portion threaded in the other.

l. A wrench having a fixed jaw, a movable jaw, a single guiding connection between said jaws, comprising a shank extending transversely from the base of one of' said jaws and a transverse guideway at the base of the other, and a jaw-adjusting screw, having a relatively fine thread, located between the working portions of said jaws and said guiding connection for adjusting the movable a`w relatively to the fixed jaw, the distance between the workin@f portion of said movable jaw and said guic ing connection being relatively great in comparison with the lengths of the contacting surfaces thereof, so as to increase the binding eect due to friction between the shank and the walls of the guideway when forces are applied to the working surfaces of said jaws, tending to separate them.

5. A wrench comprising a handle, cheek and fixed jaw formed in one piece, said jaw being thicker than said cheek, a guiding groove being formed between said fixed jaw and said handle, a movable jaw having a relatively thin plate to lie against said cheek, and provided with a guiding shank working in said guiding groove, and an adjusting screw connecting the fixed jaw to the movable jaw and mounted alongside of said shank to be out of the path of movement thereof, said guiding groove being open at the end thereof adjacent to said fixed jaw, to permit the shank to project therefrom when closing the aws.

6. A wrench comprising a handle, cheek and fixed jaw formed in one piece, said jaw being thicker than said cheek, a guiding groove being formed between said fixed aw and said handle, a movable jaw having a relatively thin plate to lie against said cheek, and provided with a guiding Shank working in said guiding groove, and an adjusting screw connecting the fixed jaw to the movable jaw, and said movable jaw having about Ithe same thickness as the fixed jaw and overhanging said cheek; said screw extending alongside of said shank.

7. A wrench comprising a head in which is formed a straight guideway open at both ends, a movable jaw extending transversely to said guideway and having a shank fitted in the guideway to move into and out of each end thereof, the shank being shorter than the jaw, a fixed jaw, and means extending alongside of said shank to adjust the movable jaw, said guideway being at the base of the fixed jaw.

8. A wrench comprising a head in whichis formed a straight guideway, open at both ends, a movable jaw extending transversely to said guideway and having a shank fitted in the guideway, the shank being shorter than the jaw, a fixed jaw, and means to adjust the movable jaw, said adjusting means placed between the shank and the jaws, the base portion of the fixed jaw being deepened to prolong the wall of the guideway, to insure constant engagement of the shank therewith, and the corresponding portion of the movable jaw being recessed to clear said deepened portion.

9. A wrench comprising a handle, cheek and fixed jaw,a guiding groove being provided between the cheek and the fixed jaw, a movable jaw dovetailed to the cheek, and means adjustably connecting the movable jaw to the fixed jaw or head, said movable jaw having an overhanging portion which is undercut, and the edge of said cheek beveled to fit said overhanging portion, and said movable jaw having a guide rib fitting in said groove at the junction of the handle and the cheek, to complete the dovetail fitting; the cheek 'occupying a position between said rib and said overhanging portion.

l0. A wrench comprising a handle, cheek and fixed jaw, a movable jaw dovetailed to the cheek, and means adjustably connecting the movable jaw to the fixed jaw or head, said movable jaw provided with a shank having part of the dovetail fitting, and said connecting means being arranged between the shank and the movable jaw.

11n A wrench comprising a handle, cheek and fixed jaw, a movable jaw dovetailed to the cheek, and means adjustably connecting the movable jaw to the fixed jaw, said movable jaw having an overhanging portion which is undercut, Aand the edge of -said cheek beveled to fit said overhanging portion, said movable jaw having an auxiliary rib fitting in a groove at the junction of the handle and the cheek, to complete the dovetail fitting, the surface of said cheek extending diagonally to form an acute angle with the groove in which said rib fits, saidconnecting means including a screw extending along said cheek between said rib and said overhanging portion, and said movable jaw movable to a closed position against the fixed jaw.

l2. A wrench comprising a handle, checky and fixed jaw or head, a movable jaw having a guide-shank between said head and said handle and fitting in a groove or guideway, said shank having a rib, and said groove having a depressed portion in which said rib is guided, said movable jaw having an undercut overhanging portion, and said cheek having an edge fitted thereto at an acute angle to the groove in which said rib fits, thereby to retain the movable jaw upon the cheek, and a screw alongside of said shank and adjustably connecting the movable jaw to the fixed jaw or head.

13. A wrench comprising a handle, cheek and fixed jaw, a movable jaw having a guide-shank, said guide-shank and said movable jaw having a dovetail tting to said cheek, said fitting including a groove, an auxiliary rib upon said shank to fit in said groove, `and a screw to connect the movable jaw to the head for relative adjustment, said cheek extending in a diagonal direction to form an acute angle With a guiding Wall of said groove, to form one portion of a dovetail fitting, and the opposite edge of said cheek being beveled, and an overhanging portion of said movable jaw being undercut, to form the other portion of said dovetail fitting, said screw an ranged between said shank and said overhanging portion, and said movable jaw movable to a closed position against the fixed aw.

14E. ln combination, a Wrench-head and cheek having a guiding groove formed with stepped portions, a movable having a shank fitting in the, stepped portions of said groove, and means extending alongside of said shank for adj ustably Connecting said movable jaw t0 said head.

l CHARLES F. MUELLER. Witnesses u R. A. MoDoNNnLL, S'riauuilz'r R. VVATKINS. 

